Hot fan for heat-treating furnaces



Nov. 9, 1954 CONE 2,694,157

HOT FAN FOR HEATTREATING FURNACES Original Filed Sept. 3, 1948 mmvrox. C arro/ Cone BY H S Attorney United States Patent HOT FAN FOR HEAT-TREATING FURNACES Carroll Cone, near Toiedo, Ohio, assignor to Surface Combustion Corporation, Toledo, Ohio, a corporation of Ohio Continuation of application Serial No. 47,6530, September 3, 1948. This application November 15, 1950, Serial No. 195,870

5 Claims. (Cl. 31058) This invention relates to a motor driven fan or blower whose impeller is disposed within a furnace chamber to circulate the atmosphere therewithin. In apparatus of this type the shaft bearing nearest the furnace chamber tends to run hot because of heat conductor thereto by that portion of the shaft which extends within the furnace chamber hence it is necessary to provide some kind of cooling system to maintain said bearing relatively cool and it is one of the objects of the invention to provide an improved cooling means for that purpose. Another object is to provide a cooling system which shall be substantially air tight as regards leakage of gaseous cooling medium into the furnace chamber. Other related features will more fully appear hereinafter.

This application is a continuation of application Serial No. 47,690 filed September 3, 1948, now abandoned.

For a consideration of what I consider to be novel and my invention, attention is directed to the following specification and the claims appended thereto.

In the accompanying drawing, the sin le figure is an axial section of a motor driven blower embodying the present invention.

The blower comprises a conventional type of impeller mounted on the projecting end of a drive shaft 11 which extends into the furnace chamber through a wall 29 thereof. Said wall will ordinarily be the bottom wall of said chamber so that the shaft may rotate about a vertical axis. Said blower is adapted to be secured to said wall 29 by a base member 23 in the form of a bell-shape structure adapted to extend within a reentrant portion of said wall 29, said structure having an outer peripheral flange 26 through which screw bolts 28 may be passed for clamping said flange t0 the outer metal casing 27 of said furnace wall 29 whereby to support said structure 23 in fixed position relative to said wall.

The hot bearing for the hot end of the shaft is indicated at 12 and is mounted within a body or head member 13 comprising a central cylindrical portion 34 wherethrough the drive shaft extends and wherein the bearing is confined by means comprising a sleeve member 36 which is secured to said head member by screw bolts 19 extending into a peripheral flange portion of said sleeve member 36. The base member 23 has an inwardly extending ledge 24 to the outer side of which said head member 13 is adapted to be clamped by bolts 25 carried by said ledge 24 and extending through a rim portion 41 of said head member 13.

The shaft 11 is driven by an electric motor whose rotor 14 is secured to the shaft and whose stator is indicated at 15 and whose housing comprises a gas tight cylindrical shell or barrel of which one end is closed by said head member 13 and whose opposite end is closed by a gas tight cap member 16 embodying a holder means 39 for supporting a shaft bearing 17, the assembly being held together by tie bolts 21 depending from the rim portion 4-1 of the head member 13. The drive shaft 11 is preferably comprised of two separate longitudinal portions of which one is a stub shaft on which the impeller 10 is mounted and of which the other is supported by the two bearings 12 and 17 and may therefore be termed the motor shaft. The stub shaft has a tapered shank adapted to be received in a correspondingly tapered socket in the motor shaft and the two parts are held together by a pull rod 37 which is screwed into said shank and thence extends through the center of the motor shaft to beyond its lower end in a bore provided in the motor shaft for that purpose, the

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lower end of the pull rod being threaded to receive a clamping nut 38. To compensate for thermal expansion of the motor shaft below the'upper bearing 12, the lower shaft bearing 17 is mounted for axial displacement along with the shaft in the holder means 39. The area of contact between said shank and said socket is reduced to a minimum by clearance spaces on the shank whereby to reduce heat conduction from the stub shaft to the motor shaft to a minimum.

The upper portion of the drive shaft 11 between the impeller 10 and the cylindrical portion 34 of the head member 13 is surrounded in spaced relation by a gas tight tubular member 22 shown as integral with the central portion of the base member 23. For a reason presently appearing it is necessary to provide a substantially gas tight seal between the adjacent ends of said tubular member 22 and the said cylindrical portion 34 of said'head member 13 and this is preferably provided by providing on said tubular member a cap-like portion 220 whose internal diameter is such as to make a snug fit with'a coaxial exterior turned portion on the cylindrical portion 34 of the headmember 13. By extending the upper end of tubular member 22 into close proximity to said impeller 10 the likelihood of foreign particles falling into said tubular member is reduced to a minimum. As will presently more fully appear the space encompassed by the bell-shaped structure of the base member 23 provides a chamber through which a gaseous cooling medium such as atmospheric air may be circulated into contact with the exterior surfaces of the head member 13 and the tubular member 22 for maintaining the upper shaft bearing 12 relatively cool. The inlet for said atmospheric air to said cooling chamber is defined by a circular row of holes 30 in the rim portion 41 of the head member 13 and the outlet for the spent air is the inlet end 32 of an exhaust pipe 43 which leads from said chamber at the ledge 24 to a source of partial vacuum such as the suction side of a blower not shown so that it is by reason of the partial vacuum that prevails in said exhaust conduit and therefore in said chamber that atmospheric air enters said cooling chamber through said inlet holes 30. A tubular baffle 31 in said cooling chamber directs the incoming air into contact with the exterior surfaces of said head member 13 and of the tubular member 22 and thence towards the exhaust outlet 32.

it is desirable to maintain the electric motor relatively cool and for this purpose the barrel 20 of the motor housing is surrounded in spaced relation by a cylindrical shell 33 having a bottom inlet 18 to provide about the barrel an annular passage 42 through which atmospheric air may flow in contact with the exterior surface of said barrel from said bottom inlet 18 to and through the circular row of holes 30 in the rim portion 41 of the head member 13, so that the partial vacuum which prevails in the cooling chamber above the head member 13 may also be effective at the inlet 18 of said cylindrical shell 33 to induce atmospheric air to enter the latter and thence flow into said cooling chamber. Since the housing for the electric motor is air tight no air can leak into the furnace chamber by way of the housing and since the joint between the tubular member 22 and the head 34 of the head member 13 is air tight no air can leak into said chamber from that point. Since the upper end of the tubular member 22 is in open connection with the furnace chamber the atmosphere prevailing in said chamber may of course enter the passage provided by said tubular member.

From the foregoing description it will now be apparent that the present invention provides a hot fan or blower that is well adapted for use with heat treating furnaces.

What i claim as new is:

1. In apparatus of the class described, in combination, a drive shaft of which one end operates in a heated and the other end in a relatively cool environment, a first bearing for the shaft, a hub member wherein said bearing is mounted and having a laterally supporting rim member, a tubular member encircling the shaft and of which one end coacts with the hub member to make a severable joint therebetween, a hood supporting and surrounding said tubular member and coacting with said rim member to define a cooling chamber about the tubular member and about the hub member, means comprising an inlet to and an outlet from said chamber for circulating a cooling medium through said chamber, and a second bearing for said shaft more remote from the hot end thereof than the first bearing.

2. Apparatus for supporting a turnable shaft on a refractory lined furnace wall with a hot end of said shaft extending to the hot side of the wall and a cold end of the shaft extending to the cold side of said wall for receiving power to turn the shaft and for support of the shaft on the wall, which apparatus comprises, in combination, gas tight shell means connected to said wall and enclosing the cold end of the shaft in a manner to seal the shaft from atmospheric air and into gas-communicating relation with the furnace atmosphere on the hot refractory side of the wall, a bearing for turnably supporting the shaft with its cold end within the shell means, support means for supporting said bearing in fixed relation to said wall, motor means within said shell means for driving said shaft, a portion of said shell means being adapted to receive heat from said shaft between its hot end and the bearing means for maintaining the latter relatively cool, and means independent of said motor means for externally cooling said portion of the shell means.

3. Apparatus according to claim 2 wherein said bearing support means comprises a hub forming a part of said shell means, said portion of the shell means comprises a tubular member of said shell means disposed concentrically about and next adjacent to said shaft to receive heat radiation therefrom, and said means for externally cooling said portion comprises wall means for ducting coolant next adjacent said tubular member whereby to constitute said tubular member a heat exchanger.

4. Apparatus according to claim 2 wherein said means forexternally cooling said portion comprises wall means for ducting coolant next adjacent said portion of the shell means whereby to constitute said portion a heat exchanger.

5. Apparatus according to claim 2 wherein said motor means comprises an electric motor which is sealed into the space encompassed by the shell means.

References Cited in the file of this patent UNITED STATES PATENTS 

